Flushing devices are used to supply water to the water intake ports of outboard motors and stern drives to clear the internal passages of the motors or to provide coolant to allow the motors to be run while they are out of the water. Exemplary of such devices are the flushing deices of U.S. Pat. No. 4,540,009 to Karls on Sep. 10, 1985 and U.S. Pat. No. 3,886,889 to Burger on Jun. 3, 1975. The Karls device uses double suction cups which has a clamping device, while the Burger device uses a water impervious sack affixed to a rigid frame member. These device are adapted to be used for outboard motors and are not suitable for inboard motors with their water intake ports on the bottom of the boat.